A battery separator needs to be produced so as to have a width (hereinafter, referred to as “product width”) that is suitable for a battery to be produced with the use of the separator. However, it is not efficient to produce a separator having such a product width at the time of production. Therefore, it is general practice to prepare a separator original sheet having a wide width, and then to simultaneously produce, by slitting the separator original sheet, a plurality of separators each having the product width.
Patent Literature 1 discloses a spot-type carbon dioxide laser cutting device as a device to slit a separator. Patent Literature 1 teaches using (i) a carbon dioxide laser oscillation unit and (ii) a mirror(s) for bending a laser beam (see paragraph [0050]).
Patent Literature 2 discloses a method for slitting a separator, which method employs a configuration in which a prescribed relationship is made between (i) an angle between a razor blade and the separator and (ii) a thickness of the separator. Patent Literature 1 teaches that the configuration of Patent Literature 2 makes it unlikely that the separator would have pores and tears (see paragraph [0030]).
Note that a separator before being slit is referred to as “original sheet”. Note also that a separator(s) after being slit is referred to as “slit separator”.